The Greatest Show on Earth

The Evidence for Evolution

(Free Press; 470 pages; $30)

Richard Dawkins, who recently retired from the Oxford University faculty, is a canny, funny and beguiling biologist.

Like a detective reconstructing a crime, he gives us dozens upon dozens of clues from the fossil record and from today's genetics laboratories to persuade us all that evolution is indeed real and that the process has in fact made us all relatives, however distant, of everything else alive.

This lavishly illustrated and detailed tribute to Charles Darwin, however well written, will probably not convince creationists nor convert believers in intelligent design. Those folks, he maintains, are "history deniers," and beyond redemption.

This is Dawkins' 10th book and arguably his best since "The Selfish Gene" and "The Blind Watchmaker." Most recently he vented his anger with a splenetic defense of atheism in "The God Delusion," but now he has largely avoided rancor and has laid out the most striking evidence with such fascinating detail that the book is both scientifically exciting and completely convincing.

Nor is the professor unaware that some religious readers who accept the evidence may still have doubts, and Dawkins restrains his militant atheism long enough to cite both the archbishop of Canterbury and the pope as among evolution's backers.

Publication of "The Greatest Show" just missed the powerful evidence of Ardipithecus ramidus - "Ardi" - a million years older than "Lucy" and at 4.2 million years old is the earliest hominid yet discovered. A female biped, her discovery was reported Oct. 9 by a team of anthropologists led by UC Berkeley's Tim D. White, and Dawkins would have loved her.

But he has plenty to remind us about the other hominids, their fossils on display in museums around the world, from Australopithecus through Homo habilis through Homo erectus to us, Homo sapiens.

And he has a wonderful tale to tell of his encounter with a stubborn creationist who insisted those evolutionary intermediates were never real and exist only in illustrations while Dawkins pleads in vain for her to look - just to look - at the hominid fossils in any museum; they are facts. The creationist is adamant, Dawkins despairs, and so should we. It is a poignant, revealing dialogue.

But to our delight Dawkins does bring us up to date with a different account of evolutionary zeal gone awry: There's a gorgeous color picture from last May's report of a creature named Darwinius masillae, the sensational lemur-like primate whose discovery was hailed in the British media "with bizarrely exaggerated hype," as Dawkins writes sadly. The same media called it the long-sought "missing link" from apes to humans and it "finally confirmed" Darwin's entire magnum opus. "Ridiculous," says Dawkins. "Darwin's theory was confirmed long ago."

But there can indeed be missing links in evolution, and one was the long absence of creatures intermediate between amphibian-like fish that swam and fish-like amphibians that walked.

And then came Tiktaalik, the brick-red fossil 375 million years old, discovered only four years ago in what was once the tropical Arctic that bore "a crocodile's head on a salamander's trunk, attached to a fish's rear end and tail," as Dawkins describes it.

And as he does again and again in this very human book, Dawkins waxes charmingly personal about Tiktaalik: "Through rose-tinted spectacles I imagined I was gazing upon the face of my direct ancestor," he writes. "Unrealistic as that was, this not-so-rose-red fossil was probably as close as I was going to get to meeting a real dead ancestor half as old as time."

So the real evidence for evolution is everywhere and in amazing detail, as Dawkins demonstrates. Goose bumps on human skin clearly derive from the hair-raising responses to fear in animals from chimps to dogs.

An "evolutionary arms race" pits cacti in the Galapagos against browsing tortoises, so the cactus grows taller to escape the browsers and the browsers evolve saddle-backed shells that enable them to stretch higher for the cacti.

And how long does evolution take? With great care Dawkins details the kinds of clocks scientists use to date their finds: radiocarbon dating can go back only 5,000 years; the known decay rates of argon isotopes let scientists go back millions, while molecular clocks, timing the rates of genetic mutations, can extend even further back in evolutionary time.

"The Greatest Show" is brilliant, detailed, anecdotal and immensely readable. It's badly needed in this era when the science of evolution is being threatened in our schools.